Birds.
The answer is bones. Bones are filled with marrow and have air spaces to make them lighter in weight.
The type of bone that contains air spaces is called spongy or cancellous bone. This type of bone is less dense than compact bone and is characterized by a mesh-like structure that provides support while making bones lighter. Spongy bone is primarily found at the ends of long bones and in the interior of flat bones.
Brachiosaurus
Bracchiosaurus A+
a ttrex
Air-filled spaces in bones are called sinuses. These are hollow cavities within the bones that help to reduce the bone's weight while maintaining strength. The most well-known sinuses are the paranasal sinuses, found in the skull bones surrounding the nasal cavity.
The medical term is "paranasal sinuses." These are air-filled cavities located within the bones surrounding the nasal cavity. They are important for natural drainage and humidifying the air we breathe.
air
Birds
sinuses.
they have no bones
The dinosaur you are referring to is likely the dinosaur called Spinosaurus. It was a large theropod dinosaur that lived in swampy areas during the Late Cretaceous period. Its bones were filled with air sacs to make it more buoyant in the water and help support its massive size.